This invention relates to the field of aluminum-based casting alloys. It further relates to automotive and aerospace parts made from such alloys.
Most aluminum casting alloys need to be solution heat treated, quenched, and artificially aged to achieve adequate properties for automotive and aerospace structural applications. The processes of solution heat treating and quenching not only increase operational and capital costs but also induce part distortion, which then requires adding a straightening step to the overall manufacturing process. That straightening step is time-consuming and a high cost operation that greatly limits the applications of cast Al alloys.
Recently, some non-heat treatable (or xe2x80x9cNHTxe2x80x9d) alloys were developed and implemented in production. Those alloys can be used in either an F-temper or T5 condition. Unfortunately, those alloys tend to have much less castability than alloys required in a T6-type temper.
The present invention consists of an Alxe2x80x94Nixe2x80x94Mn based alloy for die casting, squeeze casting, permanent mold casting, sand casting and/or semi-solid metal forming. Preferred embodiments of this alloy include the following compositional additions, all in weight percent; about 2-6% Ni, about 1-3% Mn, less than about 1% Fe, less than about 1% Si, the the balance Al, incidental elements and impurities. On a more preferred basis, this alloy composition consists essentially of about 3.5-4.5% Ni, about 1.5-2.5% Mn, less than about 0.1% Fe, less than about 0.1% Si, less than about 0.15% Ti, and less than about 0.03% B, the balance Al and incidentals.